The present invention relates to microwave measurement devices and more particularly to a small personal microwave monitor device characterized by use of a microstrip antenna and control electronics adapted to provide a field alarm, field monitor, accumulated dose alarm, and integrated dose indication of RF radiation exposure to individuals.
As is well known, there has been a dramatic increase in the use of microwave RF radiation in recent years, both in military, medical, residential, and industrial applications. Although this increase has resulted in substantial technological improvements in these fields, it has raised concern over the biological hazards of RF radiation exposure to individuals.
Recognition of this concern has promulgated regulations by various national authorities attempting to define the maximum permissable exposure of individuals to such radiation. To date, most of these regulations have dictated permissable whole body resonance exposure standards for individuals which have typically placed an average specific absorbtion level (SAR) limit on exposure in the amount of approximately 0.4 W/Kg throughout a frequency range of 0.3 to 3,000 MHz. However, more recently, the American National Standards Institute Committee has recognized that certain non-uniform heating or "hot-spot" values and part body resonances exist within particular frequency bands for which the SAR limit is in actuality too high to positively prevent biological damage to certain body parts such as the head of individuals. Thus, a need in the art exists for a microwave monitor device which is capable of accurately measuring the radiation exposure levels to individuals both throughout the normal frequency ranges of microwave radiation as well as the hot spot frequency bands.
Although this need has been recognized to a limited extent in the prior art, the microwave monitor devices to date can basically be categorized into three groups, the first being sophisticated laboratory field probes the second being portable survey monitors and the third being generic microwave monitor such as crystal monitors. The prior art sophisticated laboratory field probes and survey monitors have typically proven to be very expensive, do not accumulate exposure and are cumbersome to use in field enviroments since they require use of both hands of an individual and full attention during operation. In addition, the crystal monitors, although being substantially less expensive than the sophisticated laboratory instruments, have typically proven extremely inaccurate and thereby unreliable for field testing.
Therefore, there remains a substantial need in the art for a relatively small, portable, low-cost field monitoring device capable of accurately and continuously measuring and accumulating the exposure levels of RF radiation at specific partial body resonance frequency bands associated with hazardous "hot spots".